[Kea-users] ddns fails with powerDNS (Failed PreRequisites check)

MRob mrobti at insiberia.net
Wed Feb 6 08:44:53 UTC 2019


> Has anyone found how to make kea-ddns work with PowerDNS? pdns logs
> suggest:
> 
> pdns[20989]: UPDATE (50855) from 10.10.1.254 for lan.: Failed
> PreRequisites check, returning 6
> 
> The query log shows only some normal SELECT statements. If it's not a
> known problem can anyone show how to find what the DNS UPDATE command 
> is
> being sent to the DNS server to diagnose?
> 
> Someone else had problem but couldn't get resolution:
> https://github.com/PowerDNS/pdns/issues/5830

Problem seems to be using TSIG signed DNSUPDATE requests. There used to 
be a Kea bug

http://kea.isc.org/ticket/5071#ticket

But the link is dead. Is that bug fixed? Is the problem with Kea or 
maybe the older version of powerDNS?


Question - after I removed TSIG the initial forward and reverse 
DNSUPDATE commands succeed:
DHCP_DDNS_ADD_SUCCEEDED DHCP_DDNS Request ID xxx: successfully added the 
DNS mapping addition for this request: Type: 0 (CHG_ADD)

But Kea does another CHG_ADD only a minute later and it fails:
DHCP_DDNS_FORWARD_REPLACE_REJECTED DNS Request ID yyy: Server, 
10.10.1.254 port:5353, rejected a DNS update request to replace the 
address mapping for FQDN, wkst4.lan., with an RCODE: 8
DHCP_DDNS_ADD_FAILED DHCP_DDNS Request ID yyy: Transaction outcome 
Status: Failed, Event: UPDATE_FAILED_EVT,  Forward change: failed,  
Reverse change: failed,  request: Type: 0 (CHG_ADD)

Is this a problem or can it be ignored? Is it due to setting 
"override-no-update": true and "override-client-update": true?


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